Portable electronic devices, such as those configured to be handheld or otherwise associated with a user, are employed in a wide variety of applications and environments. The ubiquity of such devices as mobile phones, wearables, including smart watches and glasses, digital still cameras and video cameras, handheld music and media players, portable video game devices and controllers, tablets, mobile internet devices (MIDs), personal navigation devices (PNDs), other APPlication acCESSORIES (or Appcessories for short) and other similar devices speaks the popularity and desire for these types of devices. Increasingly, such devices are equipped with one or more sensors or other systems for determining the position or motion of the portable device.
Information obtained from such sensors regarding motion of a portable device has been leveraged to provide information about the behavior and physical activity of a user. In turn, this information has been extensively applied in different fields such as navigation and localization, health monitoring, emergency services, athletic training, sport rehabilitation, elderly assistance and others. For example, a portable device may provide a navigation solution having information about the user's activity to track, record and/or analyze aspects of the users motion. In one aspect, such a navigation solution may include information concerning the position, motion and/or attitude of the device. Accordingly, a complete navigation solution may include position, velocity and attitude information and a partial navigation solution may include only position and attitude, only attitude and velocity, only attitude or other combinations. A navigation solution may also include values derived from other navigation solution values, such as speed and/or distance traveled. As will be recognized, this information may be used in a variety of con texts, such as determining and assessing aspects of physical exercise in which the user may be engaged.
Notably, different navigation solutions may represent different degrees of refinement. As indicated, a complete navigation solution may include position, velocity and attitude information and a partial navigation solution may include only a subset of this information, or quantities derived from a navigation solution. Additionally, the information provided have different degrees of refinement with respect to the accuracy of some or all of the information. Generally, a more complete or more accurate navigation solution may involve a greater expenditure of resources than a less complete or less accurate navigation solution. As such, a “partial” navigation solution may include only position and attitude, only attitude and velocity, only attitude or other subsets of a complete navigation solution and may also include quantities that may be derived from a navigation solution, such as distance traveled and/or speed. However, each degree of refinement may be useful in different contexts. For example, it may be desirable to provide a relatively less refined navigation solution in a more immediate or more economical manner while different benefits, such as greater accuracy or more complete information, may be obtained from a relatively more refined navigation solution when greater resources are available.
Motion sensors, such as accelerometers, gyroscopes, magnetometers and the like may be used to provide self-contained navigation information based on extrapolating a subsequent position or orientation of the portable device relative to a previous position or orientation. Such self-contained navigation information may be used in the alternative or as a supplement to absolute sources of navigation information, i.e., reference-based techniques, such as satellite or other wireless based navigation systems. It would be desirable to leverage information from any available source, including self-contained motion sensor based information and/or absolute sources of navigation information, in order to provide a plurality of navigation solutions. Further, it would be desirable for each of the plurality of navigation solutions to represent a different degree of refinement, so that a specific allocation of resources may be used for each navigation solution. As will be described in the following materials, this disclosure satisfies these and other needs.